Selective cracking catalyst



Feb. 4, 1964 c. J. PLAYNK ETAL SELECTIVE CRACKING CATALYST Filed March23, 1960 Gasoline Advantage, Vol 9;, 4

Percent Cogelled Alumina INVENTORS. Fl Charles J.Plopk Edward J.R0s|nsk|WW M w ATTORNEY United States Patent Filed Mar. 23, 1960, Ser. No.17,016 8 Claims. (Cl. 252-455) This invention relates to an improvedsilica-alumina cracking catalyst characterized by unusual ability toselectively crack high molecular weight hydrocarbon oils to lightermaterial boiling in the range of gasoline. In one embodiment, thepresent invention is concerned with a catalytic composite of silica andalumina wherein interaction between the above components is controlledto achieve a highly selective catalyst. In another embodiment, theinvention is directed to a method for producing such catalyst.

Various processes relating to the preparation of siliceous crackingcatalysts have been described in the literature. Major effort has beendirected to the manufacture of silica-alumina cracking catalysts.Generally, these catalysts have been prepared by activation of naturallyoccurring silica and alumina-containing clays or by syntheticformulation of composites of silica and alumina. Manufacture ofsynthetic catalysts has been directed to preparation of composites ofsilica and alumina to obtain maximum interaction of the alumina with thesilica. Such purpose has generally been accomplished by reaction ofalumina-producing solutions and silica-producing solutions togetherunder conditions to achieve the formation of an intimate cogelledadmixture of silica and alumina.

In accordance with the present invention, there has been discovered animproved silica-alumina cracking catalyst wherein interaction betweenthe silica and alumina components is controlled. Control is directed, incontradistinction to previous methods for preparing syntheticsilica-alumina cracking catalysts, to minimize the content of cogelledalumina. The enhanced selectivity of the catalyst is dependent onderiving major catalytic activity from si1ica-alumina created by theinteraction of silica with alumina at a multitude of particleinterfaces. Thus, the major and more selective catalytic component ofthe present catalyst resides at the surface of finely dividedalumina-containing particles.

The present invention is concerned, in one aspect, with a method forpreparation of a catalyst consisting essentially of silica and aluminaby dispersing in a silica sol, an amount, corresponding to between about5 and about 40 percent by weight of the resulting dry composite, of afinely divided porous material characterized by a surface area of atleast 25 square meters per gram, selected from alumina and composites ofsilica and alumina containing at least about 40 weight percent alumina,which material has a weight mean particle diameter of between 1 and 5microns, the concentrations and proportions of reactants being such thatthe resulting silica sol having the aforementioned finely dividedmaterial dispersed therein has a pH of between 6 and 11 and an aluminacontent, corresponding to cogelled alumina, as hereinafter defined, inthe resulting dry composite, of less than about ice 1.5 weight percent,permitting the resulting sol to set to a hydrogel, treating theresulting hydrogel at a temperature between about F. and about 220 F.with a dilute aqueous solution of an acid or acid salt for a periodWithin the approximate range of /2 to 24 hours when an acid solution isemployed and for a period Within the approximate range of 8 to 48 hourswhen an acid salt is employed, washing the hydrogel free of watersolublematter, drying and calcining.

In another embodiment, the present invention is directed to a method forpreparing the above catalyst in the form of spheroids.

In still another embodiment, the invention described herein, isconcerned with the selective silica-alumina cracking catalyst obtainedin accordance with the forego mg process.

Thus, pursuant to the teachings of this invention, it has beendiscovered that a silica-alumina catalytic composite having unusualselective cracking ability may be prepared by incorporating in a silicasol a quantity of solid powdered alumina or silica-alumina composite,containing at least about 40 Weight percent alumina, having a weightmean particle diameter of between 1 and 5 microns. troduced is generallybetween about 5 and about 40 percent by weight and preferably betweenabout 10 and about 30 percent by weight of the resulting dry product.The concentrations and proportions of reactants are such that theresulting silica sol having the above powdered material dispersedtherein has a pH of between 6 and 11 and an alumina contentcorresponding to cogelled alumina in the resulting dry product, of lessthan 1.5 weight percent. It has been found that the hydrogel productresulting from the setting of a silica sol containing powdered materialof the aforementioned composition and particle diameter upon beingsubjected to specified acidic activation treatment and thereafterwater-washed free of soluble matter, dried and calcined at a temperaturebelow the fusion point of the powdered material afforded asilica-alumina cracking catalyst having unusual ability to selectivelycrack high molecular weight hydrocarbon oils to lighter materialsboiling in the range of gasoline.

It is a critical feature of the invention that the cogelled aluminacontent, as hereinafter defined, of the ultimate catalyst be less thanabout 1.5 percent by weight. The amount of completely interacted orcogelled alumina is designated herein as that portion of alumina whichis insoluble in a 67 weight percent aqueous solution of sulfuric acid ata temperature of 245248 F. when treated for a period of 24 hours. Incontradistinction to the present catalyst, conventional commercialsynthetic silica alumina cracking catalysts contain 3 to 5 weightpercent of completely combined, i.e., insoluble, alumina determinedunder the above conditions.

FIGURE 1 of the attached drawing depicts graphically the relationshipbetween the amount of cogelled (insoluble) alumina contained in thefinal catalyst composition and the advantage in yield of gasoline over aconventional silica-alumina cracking catalyst having a cogelled aluminacontent, as defined hereinabove, of about 3 weight percent. Referringmore particularly to The amount of such powdered material so inthisfigure, it will be seen that a marked advantage in gasoline yield wasachieved with the catalyst of the invention, characterized by a cogelledalumina content of less than about 1.5 weight percent, as compared witha conventional silica-alumina cracking catalyst having a cogelledalumina content of about 3 percent by weight. Taking into considerationvolume percent conversion to gasoline, it is evident that maximumoverall improvement Was realized with a catalyst having a cogelledalumina content, as specified above, of between about 0.5 and about 1.5weight percent.

The particular physical form of the gel product will be determinedprincipally by the use to which it is to be subjected. The processdescribed herein may be employed in preparation of the gel in anydesired physical form. Thus, the hydrosol containing added powder may bepermitted to set in mass to a hydrogel which is thereafter dried andbroken into pieces of desired size. The pieces of gel so obtained aregenerally of irregular shape. Uniformly shaped pieces of gel may beobtained by extrusion or pelleting of the powder-containing hydrogel.Also, the hydrosol may be introduced into the perforations of aperforated plate and retained therein until the sol has set to ahydrogel, after which the formed hydrogel pieces are removed from theplate. The method of the invention is especially useful as applied tothe manufacture of spherically shaped gel particles produced byintroducing drops of hydrosol into a water-immiscible liquid wherein thehydrosol sets to spheroidal bead-like particles of hydrogel. Larger sizespheres are ordinarily within the range of from about ,6 to about A inchin diameter, whereas smaller size spheres, which are generally referredto as microspheres are within the ranges of from about to about 100microns in diameter. The use of spherically shaped gel particles is ofparticular advantage as catalysts in hydrocarbon conversion processes,including the moving catalyst bed process, the fluidized process, etc.in which the spheroidal gel particles are subjected to continuousmovement. As applied to the stationary bed, spheroidal gel catalystparticles provide effective contact between the reactants and thecatalyst by avoiding channeling.

It is accordingly a preferred embodiment of the present invention toprepare the described gel catalyst product in the form of spheresalthough it is to be realized that the method hereinafter set forth mayalso be employed in obtaining a mass of gel which may thereafter bebroken up into particles of desired size. Likewise, the method describedherein may be used for the preparation of silica gels containingdispersed alumina in the form of particles of any other desired size orshape.

A silica hydrosol is prepared, in accordance with the method describedherein, containing between about 5 and about 40 percent by weight of apowdered porous material having a weight mean particle diameter of 1 to5 microns and a surface area of at least mF/g. and consisting of aluminaor a silica-alumina composite having an alumina content of at leastabout weight percent. The above particle size is an essential factor inaffording a suitable catalyst product. The powdered material may beadded by dispersing in an already prepared silica hydrosol or, as ispreferable where the hydrosol is characterized by a short time ofgelation, the powder may be added to one or more of the reactants usedin forming the hydrosol or may be admixed in the form of a separatestream with streams of the hydrosol-forming reactants in a mixing nozzleor other means where the reactants are brought into intimate contact.The powder may also be introduced into the hydrosol by the formation insitu of a finely divided alumina precipitate in one or more of thereactant streams by contacting appropriate chemicals either dissolved inreactant streams or in separate streams. Likewise, an alumina-containingpowder may be introduced in an already prepared hydrosol by dispersingtherein materials which will form a finely divided precipitate. Thelatter methods in which a precipitate is formed in the hydrosol or inreactants used in preparation thereof have generally not been found tobe as desirable as the addition of alumina-containing powder which hasbeen previously ground to the requisite particle size and thereafterintroduced into the hydrosol or during the course of hydrosol formationsince, as noted hereinabove, close control of the particle size of theadded aluminous material in the range of 1 to 5 microns is essential tothe success of the present process. As a general rule, it has been foundthat the particle size of the added aluminous material may be controlledwith greater accuracy by grinding than by precipitation, although it isto be understood that the present process contemplates the incorporationof the described powdered material in a silica hydrosol employing any ofthe foregoing or other feasible techniques.

It is, however, preferred following the teachings of this invention todisperse the fine aluminous particles in the acid solution and tosubsequently admix such solution with the silicate reactant solution.Under such conditions, the reaction time between the fine particles andacid solution is maintained at a minimum, i.e., less than one hour, toprevent excessive solution of the fine aluminous particles which wouldlead to the formation of undesired cogelled silica-alumina component.Without being limited by any theory, it would appear that when contactbetween the finely divided aluminous particles and acid solution takesplace, some reaction occurs resulting in the formation of reactivealumina interfaces on the particles. Such interfaces react with thesilica component during gelation. Subsequent treatment of the hydrogelwith acidic solution under the conditions noted hereinabove serve tocreate silica-alumina sites on the surfaces of the aluminous particles.The particular type of silica-alumina site, so formed, appears to beactive, stable and more selective than the silica-alumina catalytic siteformed by cogellation in accordance with conventional preparation.

The silica hydrosol initially formed in the present proc ess may beproduced by well known methods of reaction betwen an acid and asilicate. The acid employed may be any of those heretofore utilized inpreparation of silica hydrosols such as, for example, sulfuric,hydrochloric, nitric, acetic, phosphoric, etc. Of these, the mineralacids are preferred. Particular preference is accorded sulfuric acid.The silicate reactant may be an organic silicate, such as ethyl orthosilicate or an inorganic alkali metal silicate. The alkali metalsilicate reactant used in the preparation of the present catalysts isgenerally sodium silicate but it is contemplated that other alkali metalsilicates such as potassium silicate may, likewise, be used.

The alumina-containing powder employed may be any porous alumina havinga surface area in excess of 25 square meters per gram and preferablygreater than square meters per gram. Alumina in various phases ormixtures of phases may be employed. Thus, alpha alumina, gamma alumina,chi alumina, bauxite in anhydrous or various hydrated forms may beutilized. Highly calcined forms of alumina which are substantiallydevoid of porous structure and do not possess the requisite aboveminimum surface area are not satisfactory for use in the presentprocess. The alumina-containing powder may also be a composite ofalumina with silica such as in naturally occurring deposits of clay,kaolin, minerals, etc. or synthetic composites of silica and aluminaincluding, for example, cogelled or coprecipitated silica and alumina.Also composites of silica impregnated with alumina or aluminaimpregnated with silica may be used. The alumina content of suchcomposites should be appreciable and, in general, at least 40 weightpercent.

The particle size distribution of the aluminous powder introduced intothe silica hydrosol in accordance with the present process wasdetermined by sedimentation methods. The weight mean particle diametersWere determined by plotting the cumulative percent of alumina-containingpowder smaller than a given diameter against particle diameter, dividingthe total size range into a number of small fractions and calculating asfollows:

Weight mean diameter:

from a time prior to gelation until after the gel has been dried. Duringdrying, the hydrogel undergoes considerable shrinkage. The drying iscarried to a stage beyond that at which maximum shrinkage of the gel isobtained. The gel, a'fter syneresis or shrinkage thereof has beencompleted, is substantially dry, that is, the gel possesses open poresfree of liquid although it still contains a relatively small percentageof water which is evolved upon subjecting the gel to a relatively hightemperature. Hydrogel containing powdered alumina-containing powderdispersed therein prepared as in the present process may be dried atroom temperatures or at higher temperatures in air or steam as Well asin various inert or reducing atmospheres. While the prepared hydrogelmay be dried at ambient temperature by merely exposing to the air, it ispreferred to accelerate the removal of liquid content from the hydrogelby drying at a temperature in the range of about 150 F. to about 400 F.until shrinkage of the hydrogel is substantially complete. Drying may becarried out in air or superheated steam. Calcination of the dried gelmay be effected in an inert gas, air, steam or mixtures thereof at atemperature below that at which sintering is encountered and generallyin the approximate range of 1150 F. to 1400 for a period of about 1 houror more, generally from about 1 hour to about 24 hours.

The silica hydrosol containing finely divided dispersedalumina-containing powder is characterized by a pH within theapproximate range of 6 toll and more particularly within the range of 7to 9.5. The latter pH range has been found to be especially applicablewhen the hydrosol is formed into spheroidal hydrogel particles inaccordance with techniques described hereinabove.

The resulting silica hydrogel thaving finely divided alumina-containingpowder dispersed therein is, in accord ance with the method of theinvention, subjected to treatment with an acidic solution having a pHless than about at a temperature between about 150 and about 220 F. fora period extending from /2 hour to 48 hours, depending on the nature andconcentration of the acidic treating solution. Thus, it is preferred toutilize a dilute aqueous treating solution containing less than aboutpercent by weight of the acidic compound. Both acids and acid salts maybe employed as the acidic compound. More particularly, it has been foundthat when an acid solution is employed, the period of treatment shouldbe within the approximate range of /2 to 24 hours and when an acid saltsolution is employed the period of treatment should extend from 8 to 48hours. While any acid or acid salt which does not adversely aifect thecatalytic properties of the resulting product may apparently beemployed, a mineral acid and particularly, sulfuric acid is preferredamong the acids and ammonium and aluminum acid salts are preferred amongthe acid salts.

The hydrogel after acid treatment may optionally be base-exchanged witha suitable aqueous solution containing an ion capable of replacing anyremaining zeolitic alkali metal, which ion does not detn'mentallyaflfect the finished catalyst. Generally, it has been found thatsubsequent base-exchange after the acid treatment is unnecessary sincezeolitic alkali metal contained in the hydrogel before the acid treatingstep is, under the conditions of such treatment, noted hereinabovesubstantially or entirely removed during the acid treating step.

The hydrogel after acid treatment or after base-exchange, if such stepis employed, is water washed free of soluble matter. The washed hydrogelis then dried, sui-tably in an atmosphere of superheated steam, at atemperature of about 150 F. to about 400 F. The dried product isthereafter calcined suitably in an atmosphere of air and/or steam, at atemperature of 1150 F. to 1400 F. to yield the fiinished catalyst.

Catalytic hydrocarbon conversion, utilizing the catalyst describedherein may be carried out at catalytic cracking conditions employing atemperature within the approximate range of 700 F. to 1200 F. and undera pressure ranging from sub-atmospheric up to several hundredatmospheres. The contact time of the oil with the catalyst is adjustedin any case according to the conditions, the particular oil feed and theparticular results desired to give a substantial amount of cracking tolower boiling products.

The cracking activity of the catalyst is a measure of its capacity tocatalyze conversion of hydrocarbons and is expressed herein as thepercent conversion of a Mid- Continent gas oil having a boiling range of450 to 950 F. to gasoline having an end point of 410 F. by passingvapors of the said gas oil through the catalyst at 875 'F.,substantially atmospheric pressure and a feed rate of 1.5 volumes ofliquid oil per volume of catalyst per hour for ten minute runs betweenregenerations.

Cracking activity of the catalyst of the present invention and acomparable control catalyst consisting of a commercial silica-aluminacracking catalyst containing about 10 weight percent total aluminacontent and about 90 weight percent silica were determined in accordancewith the following examples which will serve to illustrate the catalystand method of the invention without limiting the same:

Example 1 I in a solution of sulfuric acid as follows:

A. Acid-alumina fines solution (1) 4.42 lbs. of 96.7% H

20.6 lbs. of H 0 (2) 17.59 lbs. aqueous slurry 0t Al O -3H O containing20% wt. A1 0 11.79 lbs. H 0

Solution 2 was added slowly to solution 1 while agitating vigorously toprevent agglomeration of the fines. The final solution A had a specificgravity of 1.121 at 68 F.

Solution A above was mixed with an aqueous sodium silicate solutionhaving a specific gravity of 1.206 at 81 F. and characterized by thefollowing composition:

B. Silicate solution:

33 lbs. of N-Brand sodium silicate containing 28.85 wt. per cent Si0 22lbs. of H 0 Four hundred (400) cc./ min. of the silicate solution werecontacted with 392 cc./min. of the acid-fines solution in a mixingnozzle, forming a hydrosol having a pH of 8.5.

The resulting hydrosol was introduced in the form of globules into awater-immiscible oil medium wherein the globules set to hydrogel beadsin 2.0 seconds at a hydrosol temperature of 59 F.

After formation the hydrogel beads were Water-rinsed free of oil andcovered with a 2 weight percent aqueous sulfuric acid solution volume ofacid solution/volume hydrogel). The hydrogel Was then heat treated inthe acid solution at 200 F. for 2 hours, reducing the hydrogel pH from8.5 to 3.6. The acid-treated hydrogel was then base-exchanged with 3two-hour and one overnight (20 hours) change with 2 percent by weightaqueous ammonium chloride solution. The base-exchanged product waswater-washed free of chloride and sulfate ions, air dried at 270 F. for20 hours, calcined in air for 10 hours at 1200 F. and stabilized with a20 hour steam treat at 1225 F. with steam at atmospheric pressure.

The resulting catalyst was characterized by a surface area of 203 m./g., an alumina content of 23.0 weight percent, a sodium content of 0.08weight percent, a sulfate content of 0.09 weight percent and an apparentdensity of 0.6 g./cc.

The above catalyst was tested for catalytic cracking activity by passingthereover a charge of a Mid-Continent gas oil having a boiling range of450 to 950 F. at a reactor temperature of 875 F., a LHSV of 1.5 atatmospheric pressure. The results obtained presented in Table Ihereinbelow show a conversion of 54.4 volume percent aifording +3.3volume percent more RVP gasoline than standard silica-alumina catalystat the same conversion. The excess C s were lower by 1.6 volume percent.An advantage in dry gas of 1.2 weight percent and 0.7 weight percentcoke were also realized.

EXAMPLE 2 The catalyst of this example was prepared in the same manneras in Example 1 except that the base-exchange step with ammoniumchloride was eliminated to determine whether substantially all thebase-exchange had occurred during the previous heat acid treating step.

Catalytic cracking evaluation of this catalyst was carried out under thesame conditions as in Example 1. The results obtained are set forth inTable I hereinbelow and show a conversion of 51.6 volume percentaffording a +3.5 volume percent more 10 RVP gasoline, +2.5 volumepercent excess C s, +1.4 dry gas and +0.2 weight percent coke overstandard silica-alumina catalyst at the same conversion.

It will be evident from a comparison of the results obtained with thecatalysts of Examples 1 and 2 that sub stantially complete base-exchangeof the hydrogel had been accomplished during the hot acid treating step,making subsequent treatment with the ammonium chloride solutionunnecessary.

EXAMPLE 3 The catalyst of this example was formed in the same manner asin Example 1. The hydrogel beads, after being washed free of formingoil, were covered with a 5 weight percent aqueous aluminum sulfatesolution /2 volume of solution/ volume hydrogel). The hydrogel was thenheat treated in such solution at 200 F. for 4 hours reducing thehydrogel pH from 8.5 to 3.5. The treated hydrogel was then water-washedfree of sulfate ions, dried in air at 270 F. for hours, calcined in airat 1200 F. for 10 hours and stabilized by treating with steam atatmospheric pressure for 20 hours at 1225 F.

Catalytic cracking evaluation of this catalyst was carried out under thesame conditions as in Example 1. The results obtained are presented inTable I hereinbelow and show that while this catalyst is active, givinga 51.6 volume percent conversion, it does not possess the selectivityadvantage over the standard silica-alumina catalyst such as achievedwith the catalysts of Examples 1 and 2.

The conditions of formation and the cracking evaluation results obtainedfor the above catalysts are set forth in the following table:

Table I Example N o 1 2 3 Description Silica gel plus 25% A; as alphaAl203'3HzO formed at 8.5 pH

Ilyilrogel Activation:

Solution H3504 H2304 00110., percent Wt 2 2 5 Time, Hrs 2 2 4 Temp., F200 200 200 Final Gel, pH. 3 G 3.0 3 5 Base Exchange:

Solution NII4C1 None None Cone percent Wt 2 No. Changes 4 PhysicalProperties:

Apparent Dons, g./ce 0. 65 0.87 0.77

Steamed 1 Surface Area, In. /g.

Fresh 537 506 498 Steamed 203 Analysis:

Na, percent Wt 0.08 0. 43 0.29 S04. percent Wt 0. 09 0. 09 0. 09 A1 0percent Wt.

Total 23. 0 22. 2 24. 9 Combined 2 0.68

Evaluation of Steamed 1 Catalysts Conversion, Vol. percent 54. 4 51. G51. 6 10 RVP Gasoline, Vol. percent..- 42.2 41. 0 37. 7 C Gasoline, Vol.percent 40. 5 39. 3 36. 3 Total C s, Vol. pereent 15. 3 13. 8 10. 7 DryGas, Wt. percent. 6. 0 5. 3 0.1 Coke, Wt. percent 3. 2 3. 2 3. 3 Delta:1

10 RVP Gasoline, V01. percent"..- +3. 3 +3.5 +0.2 X304, Vol. percent 1.62. 5 0. 7 Dry Gas, Wt. percent. -1.2 1.4 0. 0 Coke, Wt. percent -0. 70.2 0.1

1 Steamed 20 hours at ]225 F. with 100% steam at atmos. pressure.

hResiduaI A1 0 after treating catalyst fines with hot 67% H 30 for 24ours.

3 Delta difference between catalysts and standard silica aluminacatalyst at the same conversion.

From a comparison of the above tabulated results, it will be seen thatthe most active and selective cracking catalyst was obtained at theshort hydrogel activation time, utilizing hot acid as the activatingmedium.

The following examples serve to show the effect of acid activatingtemperature, concentnation and time on catalytic properties of thepresent catalyst.

EXAMPLE 4 The catalyst of this example was prepared in the same manneras in Example 1 except that the hydrogel was treated with the 2 weightpercent aqueous sulfuric acid solution for 24 hours at room temperature(7080 F.).

Catalytic cracking evaluation of this catalyst was carried out under thesame conditions as in Example 1. The results obtained show thatinsufficient activation has taken place. The catalyst obtained had a47.5 volume percent conversion, i.e., approximately 7 volume percentless than that of the catalyst of Example 1. The selectivity of thiscatalyst is also poorer, affording only +2.5 volume percent moregasoline than the standard silicaalumina catalyst at the sameconversion.

EXAMPLE 5 The catalyst of this example was prepared in the same manneras in Example 1 except that the hydrogel was treated with a 5 Weightpercent aqueous sulfuric acid solution for 24 hours at room temperature(7080 F.). The acid treated hydrogel was then water washed free ofsulfate ions and dried, calcined and stabilized as in Example 1.

Catalytic cracking evaluation of this catalyst was carried out under thesame conditions utilized in Example 1. The results obtained show thattreatment with the 10 Catalytic cracking evaluation of this catalyst wascarried out as above and the results obtained established that thecatalyst was not vsubstantially difierent from that of Example 1.

The results of the above Examples 4-7, together with those of Examples 1and 2, are shown in Table II below:

Table 11 Example No 4 5 6 1 7 2 Description Silica gel plus 25% A1203 asalpha AltOs-3H lformed at 8.5 pH

Hydrogel Activation:

301111710 H2501 H2SO4 H2804 HzSO4 H2804 HZSO4 00110., Percent Wt 2 5 3 22 2 Time, Hrs 24 24 5 2 4 2 Temp., F. R.T. R.T. 150 200 200 200 FinalGel p 1.9 1. 6 2. 2 3. 6 3.1 3.0 Base Exchange:

Solutio NH401 No No NH4C1 NH;C1 No Conc., Percent Wt 2 2 2 No. changes 44 4 Physical Properties:

Apparent Dens., g.lcc.-

Fresh Steamed 1 0.66 0.65 0.72 0.87 Surface Area, m. /g.

resh 553 520 492 536 522 506 Steamed 1 244 207 189 203 191 175 Analysis:

Na, Percent Wt 0. 09 0.07 0.16 0.08 0.05 0. 43 S04, Percent Wt 0.09 0.09 0. 09 0. 09 0.09 0. 09 A1203, Percent Wt.

Total 23.8 19. 9 20. 5 23.0 23. O 22. 2 Combined 2 0.68

EVALUATION OF STEAMED 1 CATALYSTS Conversion, Vol. Percent 47. 5 50. 253. 8 54. 4 55. 6 51. 6 10 RVP Gasoline, Vol. Percent" 38.1 39.2 41.742.2 43.0 41.0 0 Gasoline, Vol. Percent... 36.4 37. 5 40. 2 40. 5 41. 439. 3 Total 0 ,s, Vol. Percent 12.6 13.1 14. 6 15.3 15.8 13.8 Dry Gas,Wt. Percent 5.2 5. 6 5.8 6.0 6.2 5.3 Coke, 5ft. Percent 2.7 3.7 3.9 3.23.1 3. 2 Delta:

10 RV]? Gasoline, Vol. Percent 2. 5 +2.3 +3.1 3.3 +3.6 +3.5 XsCl, Vol.Percent 2. 1 2. 6 2. 4 -1. 6 2. 0 2. 5 Dry Gas, Wt. Percent -1.1 0.9 1.3-1.2 1.2 1.4 Coke, Wt. Percent 0. 4 +0. 4 +0. 2 -0.7 O.9 0. 2

1 Steamed hours at 1225 F. with 100% steam at atmospheric pressure. 2Residual A1 03 after treating catalyst fines with hot 67% H2804 for 24hours. 3 Delta difference between experimental catalysts and standsillca-alumma catalyst at the same conversion.

higher sulfuric acid concentration at room temperature serves toincrease the conversion to 50.2 volume percent but did not substantiallyimprove the selectivity over that achieved with the catalyst of theprevious example. In addition, the coke make obtained with the catalystof the present example was +0.4 weight percent greater than thatobtained with the standard silica-alumina catalyst at the sameconversion.

EXAMPLE 6 The catalyst of this example was prepared in the same manneras in Example 1 except that the hydrogel was treated with a 3 weightpercent aqueous sulfuric acid treatment for 5 hours at 150 F. The acidtreated hydrogel was then water-washed free of sulfate ions and dried,calcined and stabilized as in Example 1.

Catalytic cracking evaluation of this catalyst was carried out under thesame conditions utilized in Example 1. The results obtained show goodactivity, 53.8 volume percent conversion, as well as a +3.1 volumepercent gasoline advantage over the standard silica-alumina catalyst.The excess C s was 2.4 volume percent and dry gas was +1.3 weightpercent in comparison to that obtained with the standard catalyst.

EXAMPLE 7 The catalyst of this example was prepared in the same manneras in Example 1 except that the hydrogel was treated with the 2 weightpercent aqueous sulfuric acid solution for 4 hours at 200 F.

It will be seen from the foregoing data that hot acid activation for 2to 4 hours at about 200 F. afforded a catalyst of maximum improvement.Lower temperatures and higher acid concentration show lower selectivityin gasoline advantage and in some instances the coke make is greaterthan the standard silica-alumina cracking catalyst.

The following example illustrates that the cracking catalyst describedherein can also be activated by heat treating the hydrogel in a hot acidsalt solution, such as a 5 percent by weight aqueous solution ofaluminum sulfate.

EXAMPLE 8 The catalyst of this example was prepared in the same manneras in Example 1 except that, in place of treating with acid, thehydrogel was treated with 5 weight percent aqueous aluminum sulfatesolution for 21 hours at 200 F. using /2 volume of such solution pervolume of hydrogel. The treated hydrogel was then water washed free ofsulfate ions and dried, calcined and stabilized as in Example 1. Thefinished catalyst had a surface area of 182 m. /g., a sodium content of0.21 weight percent, a sulfate content of 0.09 weight percent and analumina content of 24.9 weight percent.

Catalytic evaluation of this catalyst, carried out as above, showed goodconversion, 53.8 volume percent and a selectivity of +3.0 volume percentgasoline, 1.9 volume percent excess C s and a 0.5 weight percent cokeadvantage over standard silica-alumina cracking catalyst.

Table III Example No 3 8 Description Silica gel plus 25% wt. A1203 asalpha 11120 31120 Hydrogel Activation:

Solution Cone, Percent Wt- 5 Time, Hrs 4 21 Temp., F.- 200 200 Final GelpH.. 3. 5 3.5 Base Exchange None None Physical Properties:

Apparent Dens., g./ec.

Fresh--. Steamed l O. 77 0.73 Surface Area, 111. 7g.-

resh 498 494 Steamed l 180 182 Analysis:

Na, Percent Wt 0.29 0.21 S04, Percent; Wt. 0. 09 0. 09 A1 03, PercentWt.-

Total 24. 9 24. 9 Combined 2 1. 48

EVALUATION OF STEAMED CATALYSTS Conversion, Vol. Percent 51. 6 53.8 10RVP Gasoline, Vol. Percent- 37. 7 42.3 Gasoline, Vol. Percent. 36. 3 40.8 Total C4s, Vol. Percent 16. 7 16.0 Dry Gas, Wt. Pcrcent--.. 6.1 6.3Coke, Wt. Percent 3. 3 3. Delta: 3

RVP Gasoline, Vol. Percent +0. 2 +3.0 X50 Vol. Percent 0. 7 1. 9 DryGas. Wt. Percent 0. 6 -1 2 Coke, Wt. Percent 0. 1 0. 5

1 Steamed 20 hours at 1225 F. with 100% steam at atmospheric pressure 1Residual A120 after treating catalyst fines with hot 67% 11130 for 24hours.

3 Delta difference between experimental catalysts and standardsilicaalumina catalyst at the same conversion.

It will be seen from the above results that while activation with thealuminum sulfate solution at 200 F. for 21 hours afforded a highlyeffective catalyst, treatment for 4 hours under the same conditions wasnot sufiicient to activate the hydrogel. Thus, it is evident thatactivation can be accomplished in an acid salt solution, providing thatsuch activating treatment is of suflicient duration.

The following examples illustrate the necessity for controlling theamount of interaction between the alumina fines and acidic solution.Increased interaction between the fines and acid solution has been foundto result in the formation of cogelled silica-alumina content, which, asnoted hereinabove, has been found to effect a reduction in the desiredcatalytic selectivity. The control of cogelled alumina was achieved byintroducing alumina, as aluminum sulfate, into the acid solution to addrespectively 1, 2 and 3 percent by weight of alumina as a cogelledcomponent.

EXAMPLE 9 The catalyst of this example was prepared in the same manneras in Example 1 except that to the sulfuric acid forming solution wasadded sufficient aluminum sulfate to contribute an additional 1 percentby weight, on the finished catalyst basis, of cogelled alumina. Theresulting aluminum sulfate-sulfuric. acid solution was mixed with thesame silicate solution used in Example 1. The hydrogel so obtained,formed at a pH of 8.5, was found to contain 25 weight percent alumina asfines and 1 weight percent alumina is cogelled alumina resulting fromthe introduced aluminum sulfate. The hydrogel product obtained wasthereafter acid activated and processed in a manner identical with thatdescribed in Example 1.

EXAMPLE 10 The catalyst of this example was prepared in the same manneras in Example 9 except that to the sulfuric acid forming solution wasadded sufiicient aluminum sulfate to contribute an additional 2 percentby weight, on the finished catalyst basis, of cogelled alumina, so thatthe hydrogel product contained 25 weight percent alumina as fines and 2weight percent alumina as cogelled alumina.

EXAMPLE 1 1 The catalyst of this example was prepared in the same manneras in Example 9 except that to the sulfuric acid forming solution wasadded sufficient aluminum sulfate to contribute an additional 3 percentby weight, on the finished catalyst basis, of cogelled alumina, so thatthe hydrogel product contained 25 weight percent alumina as fines and 3weight percent alumina as cogelled alumina.

The results obtained upon catalytic evaluation of the catalysts ofExamples 9-11 as well as for a catalyst prepared in a manner identicalto that of Example 1, referred to herein as Example 1A, are shown in thetable below:

Table IV Example No 1A 9 10 11 Description Silica gel plus 25% A140 asalpha Al 0 -3HzO formed at 8.5 pH

Hydrogel Activation:

Solution 1123024 H1302.) H2504 H1504 2 2 2 2 2 2 200 200 200 200 FinalGel pI-I 2. 9/3. 3 3. 5 3. 5 3.0 Wt. Percent Cogelled A1 04 0 1 2 3 BaseExchange:

Solution NH C1 NH4C1 NII C] NII C1 Conc., Percent Wt. 2 2 2 No. Changes4 4 4 4 Physical Properties:

Apparent Dens., g./cc.-

Fresh Steamed 1 0. 74 0.79 0. 86 0.86 Surface Area, m./g.

Fresh 488 464 483 415 Steamed l 203 181 108 153 Analysis:

Na, Percent Wt 0. 0.12 0.07 0.16 S0 Percent \Vt 0. 09 0. 09 0. 09 0. 09A140 Percent Wt.

Total 22. 9 24. 3 24. 9 24. 4 Combined 1 1.02 1. 38 1.44 2.19

EVALUATION OF STEAMED CATALYSTS Conversion, Vol. Percent- 54. 4 56. 356. 7 56. 2 10 RVP Gasoline, Vol. Percent 42. 5 42. 5 42. 2 42.]. 0Gasoline, Vol. Percent.-- 40. 4 41. 3 40. 8 40. 6 Total C4s, Vol.Percent 16. 6 16. 5 1G. 9 16.3 Dry Gas, Wt. Percent 6. 3 6. 0 6. 7 6.5Coke, Wt. Percent 3. 2 3. 4 3. 7 3.8 Delta:

10 RVP Gasoline, Vol.

Percent +3. 6 +2. 7 +2. 3 +2. 5 X504, Vol. Percent 3. 2 1. 2 1. 3 1.6Dry Gas, Wt. Percent..- 0. 9 0. 9 0.9 1.0 Coke, Wt. Percent 0. 6 0. 7 0.4 0. 2

u zss telamed 20 hours with steam at atmospheric pressure, at 24 1 Residua1 A1204 after treating catalyst fines with hot 67% H4804 for lOlllS.3 Delta difference between experimented catalysts and standardsilicaalumina catalyst at the same conversion.

It is evident from the foregoing data that the added alumina, ascogelled component, which would result from excessive alumina fines-acidinteraction increases conversion. However, the added alumina as cogelledalumina shows reduced selectivity advantage over standard silicaaluminacatalyst. Gasoline selectivities of +2.3 to +2.7 volume percent comparedto +3.6 volume percent for the catalyst containing no additionalcogelled alumina were realized. Economically a 1 percent loss ingasoline EXAMPLE 12 The catalyst of this example was prepared in thesame manner as in Example 9 except that the 'hydrogel product, insteadof being treated with sulfuric acid activating solution, was treatedwith a 5 percent by weight aqueous solution of alumintun sulfate for 20hours at 200 F. After such treatment, the hydrogel product was Washed,dried, calcined and steam. treated as described in Example 1.

EXAMPLE 13 The catalyst of this example was prepared in the same manneras in Example 10 except that the hydrogel product, instead of beingtreated with sulfuric acid activating solution, was treated withaluminum sulfate solution and processed as in the preceding example.

EXAMPLE 14 The catalyst of this example was prepared in the same manneras in Example 11 except that the hydrogel product, instead of beingtreated with sulfuric acid activating solution, was treated withaluminum sulfate solution and processed as in Example 12.

The results obtained upon catalytic evaluation of the catalysts ofExamples 12-14, as well as for the catalyst of Example 8, are shown inthe table below:

Table V Example N 8 12 13 14 Silica gel plus 25% A120 as alphaDescription Al203-3H2O formed at 8.5 pH

. 5 5 5 5 Y 20 20 20 20 200 200 200 200 Final Gel pH 3. 5 3. 5 3. 6 3. 7Wt. Percent Cogelled A1 03 0 1 2 3 2 No. Changes 4 4 4 4 PhysicalProperties:

Applarent Dens., g./cc.-

r Sseamed 1 0.73 0.77 0.77 0.81 Surface Area, mfl/g res 494 440 503 501Steamed 182 191 192 188 Analysis:

Na, Percent Wt 0.21 0.15 0.05 0. 08 S04, Percent W't 0.09 0.09 0. 09 0.09 A1203, Percent Wt.-

Total 24. 9 29. 0 26. 8 27.0 Combined 2 1. 48 1. 73

EVALUATION OF STEAMED 1 CATALYSTS Conversion, Vol. Percent 55. 8 58. 453.8 58. 5 10 RVP Gasoline, Vol. Percent 42.3 42.3 38.8 42.5 05+Gasoline, Vol. Percent 40.8 41.0 36.9 41.3 Total Cis, Vol. Percent 16. 018.3 17.1 18. 5 Dry Gas, Wt. Percent 6.3 7.1 7.2 6.6 Coke, Wt. Percent3. 5 3. 9 4.0 4.1 Dcltar 10 RVP Gasoline, Vol. Per- 1 Steamed 20 hourswith 100% steam at atmospheric pressure, at 1225F.

2 Residual A120; after treating catalyst fines with hot 67% H2804 for 24hours.

3 Delta difference between experimented catalysts and standardsilicaalumina catalyst at the same conversion.

It will be seen from the above data that a cogelled alumina content ofabove 1.5 weight percent was definitely detrimental to the desiredselectivity advantage over the standard silica-alumina catalyst.

The following examples illustrate the elfect of alumina fines content onthe catalytic characteristics of the resulting catalyst. In addition, acomparison is also made in this study of the effect of eogelled aluminaarising from the solution of alumina fines during an extended fines-acidcontact period of 2 hours instead of the usual 0- /2 hour periodinvolved in forming the bead catalyst.

EXAMPLE 15 The catalyst of this example was prepared by dispersing 12.5percent by weight A1203, on the ultimate catalyst basis, as alphaalulmina trihydrate milled fines in the acid solution used to formsilica gel by reaction with the silicate solution. The fines in thisexample were milled 72 hours in a 20 percent by weight aqueous aluminaslurry. The resulting slurry contained finely divided alumina having aweight mean particle diameter of 1.46 microns. A quantity of such slurrywas dispersed in a solution of sulfuric acid as follows.

A. Acid-alumina fines solution:

(1) 4.76 lbs. of 96% H 50 22.10 lbs. of H 0 (2) 9.49 lbs. aqueous slurrya Al O -3H O- containing 20% wt. A1 0 22.1 lbs. of H 0 Solution 2 wasadded slowly to Solution 1 while agitating vigorously to preventagglomeration of the fines. The final solution A had a specific gravityof 1.084 at 77 F.

Solution A above was immediately mixed with an aqueous sodium silicatesolution, having a specific gravity of 1.206 at 81 F. and characterizedby the following composition.

B. Silicate solution:

33 lbs. of N-Brand sodium silicate 22 lbs. of H 0 Four hundred'sixteen(416) cc./min. of the acid-fines solution were contacted with 402cc./min. of the silicate solution in a. mixing nozzle, forming ahydrosol having a pH of 8.4. The resulting hydrosol was introduced inthe form of globules into a water immisible oil medium wherein theglobules set to hydrogel beads in 1.9 seconds at a hydrosol temperatureof 58 F.

After formation, the hydrogel beads were water rinsed free of oil andcovered with a 2 weight percent aqueous sulfuric acid solution /2 volumeof acid solution/ volume hydrogel). The hydrogel was then heat treatedin the acid solution at 200 F. for 2 hours, reducing the hydrogel pHfrom 8.4 to 3.0. The acid-treated hydrogel was then base-exchangedemploying three 2-hour and one overnight (20 hours) treating periodswith 2 percent by weight aqueous ammonium chloride solution. Thebaseexchanged product was water washed free of chloride and sulfateions, air dried at 275 F. for 20 hours in air, calcined in air for 10hours :at 1000 F. and steam treated 20 hours at 1225 F. in percentatmospheric steam.

EXAMPLE 16 The catalyst of this example was prepared in the same manneras in Example 15 except that the alumina fines were contacted for 2hours at room temperature (7080 F.) with the sulfuric acid solutionbefore admixing with the silicate solution. The resulting hydrogel wasthen processed as in Example 15.

EXAMPLE 17 The catalyst of this example was prepared in the same manneras in Example 15 except that the hydrogel, instead of being treated withan acid, was heat treated in a 5 weight percent aqueous solution ofaluminum sulfate for 24 hours at 200 F. The treated hydrogel wasthereafter base-exchanged and processed as in Example 15.

The results obtained upon catalytic evaluation of the catalysts ofExamples 15-17, as well as for the catalyst of Examples 1A and 8, areshown in the table below:

Table VI Example No 1A 15 4 16 8 17 Description. percent Wt. A1103 fines25 12.5 12.5 25 12.5

Hydrogel Activation:

Solution H2804 H2804 H1804 Conc., percent Wt 2 2 2 5 5 H 2 2 20 24 200200 200 200 3.0 3.0 3. 5 3.0

ution NH Cl NH CI NH Cl None NILCI Cone.. Wt. percent. 2 2 2 2 No.Changes 4 4 4 4 Physical Properties:

Apparent Dens.,

glee.-

Fresh Steamed 1 0. 74 0.82 0.91 0.73 0. 64 Surface Area,

in /g.-

Fresh. 488 505 454 494 518 Steamed 1 203 181 164 182 209 Analysis:

NA, percent Wt- 0.12 0.11 0.14 0.21 0.13 S04, percent Wt-.-- 0. 09 0. 090. 09 0. 09 0. 09 AlzO3,DBICO11t Wt.-

T a] 22. 9 14.1 13.5 24. 9 15.2 Combined 1.02 0. 93 1. 32 1. 48 1. 30

EVALUATION OF STEAMED 1 CATALYSTS Conversion, Vol.

percent 54. 4 51. 8 50. 5 53. 8 52. 6 10 RVP Gasoline,

Vol. pereent 42. 5 41.0 39. 2 42.3 41.9 C +Gaso1ine, V

percent 40.4 39. 3 37. 6 40.8 40. 1 Total C(s, Vol

percent 16. 6 13.6 13. 3 10. 14.0 Dry Gas, Wt. percent. 6. 3 5. 7 5. 76.3 5. 8 Coke, Wt. percent.-.. 3. 2 3.2 3. 7 3. 2. 6 Delta 10 RVPGasoline,

Vol. percent +3. 6 +3. 3 +2. 2 +3.0 +3. 8 X504, Vol. percent. 3. 2 2. 92. 5 1. 9 2. 8 Dry Gas. Wt.

percent 1.1 0. 9 -1. 2 1. 1 Coke, Wt. percent- 0. 6 0. 3 0. 4 --0. 5-1.0

1 Steamed 20 hours with 100% steam at atmospheric pressure. at 1225F.ilResidual AIQO alter treating catalyst fines with hot 67% H 80 for101115.

3 Delta difierenee between experimental catalysts and standardsilicaalumina catalyst at the same conversion.

4 Fines'aeid contact 2 hours at room temperature.

It will be seen from the foregoing data that the catalyst of Example wascharacterized by a catalytic activity and selectivity quite similar tothat of Example 1A, even though the catalyst of Example 15 contains only12.5 weight percent A1 0 as fines whereas the catalyst of Example 1Acontained 25 weight percent A1 0 as fines. Catalytic evaluation of thecatalyst of Example 16 shows the disadvantage of the added cogelledalumina component arising from the fines-acid solution during theextended fines-acid contact of 2 hours at room temperature. Conversion,utilizing this catalyst, was about 1% lower than for the catalyst ofExample 1.5 and. the selectivity was 16 about 1% less gasoline advantageover the standard silicaalumina catalyst. The data of Table VI also showfrom a comparison of the evaluation results obtained with the catalystsof Examples 8 and 17 activated by treatment with hot aluminum sulfatesolution that the lower alumina content catalyst, i.e., Example 17, wassuperior in gasoline advantage, dry gas and coke over the catalyst ofExample 8 activated in a similar manner but containing 25 weight percentA1 0 fines.

The following examples, summarized in Table VII hereinbelow, illustratethat active and selective cracking catalysts are capable of preparationin accordance with the method of the invention utilizing sources ofalumina other than alpha alumina trihydrate described above.

EXAMPLE 18 The catalyst of this example was prepared in the same manneras in Example 1 except that the fines used were gamma alumina, knowncommercially as Alcoa F-l0 alunnna.

Catalytic evaluation of this catalyst showed a good conversion, 51.6volume percent and a good selectivity advantage, +3.2 volume percentgasoline, 3.9 volume percent excess C s and -0.9 weight percent dry gasover the standard silica-alumina catalyst.

EXAMPLE 19 The catalyst of this example was prepared in the same manneras in Example 1 except that the alumina source was raw Georgia kaolinclay. The resulting catalyst showed a gasoline advantage of +2.4 volumepercent over the standard silica-alumina catalyst.

EXAMPLE 20 The catalyst of this example was prepared in the same manneras that of Example 19 except that instead of activation of the hydrogelby treatment with sulfuric acid, activation was effected by treatingwith a 5 percent by weight aqueous aluminum sulfate solution at 200 F.for 20 hours. The catalyst obtained showed a gasoline advantage of +3.0volume percent over the standard silicaalumina catalyst.

EXAMPLE 21 The catalyst of this example was prepared in the same manneras in Example 1 except that the alumina source was a calcined (16 hoursat 1400" F.) Georgia kaolin clay. The resulting catalyst showed agasoline advantage of +2.9 volume percent over the standardsilica-alumina catalyst.

EXAMPLE 22 The catalyst of this example was prepared in the same manneras that of Example 21 except that instead of activation of the hydrogelby treatment with sulfuric acid, activation was effected by treatingwith a 5 percent by Weight aqueous aluminum sulfate solution at 200 F.for 2 0 hours. This catalyst also showed a definite improvement ingasoline yield over the standard silica-alumina catalyst.

EXAMPLE 23 The catalyst of this example was prepared in the same manneras that of Example 21 except that the clay fines and sulfuric acidsolution were contacted for two hours before admixture with the silicatesolution to form the bead hydrogel. Since the calcined clay isrelatively slowly soluble in acid, a moderately long contact time withthe acid is satisfactory. The resulting catalyst showed a markedgasoline advantage of +3.3 volume percent over the standardsilica-alumina catalyst.

The results obtained utilizing the catalysts of Examples 18-23 aresummarized in Table VII below:

of silica and alumina containing at least 40 weight percent alumina,which material has a weight mean particle Table VII Example No 18 19 2021 22 23 Description Silica gel Silica gel 25% 25% ClayRaw Silica gel25% clay -1203 Georgia Clay Oalcined Georgia Clay F-lO HydrogelActivation:

SOhltlOH H2304 H2304 H2304 H2304 Cone, Percent Wt 2 2 2 5 2 Time, Hrs 24 20 4 20 2 Temp., F 200 200 200 200 200 200 Final Gel pH 2. 4 2.6 3. 23. 6 3. 8, 3. 5 Base Exchange:

Solution NH C1 NH4C1 NH4O1 NH4C1 NHlCl NH O1 Cone, Perce 2 2 2 2 2 2 No.Changes" 4 4 4 4 4 4 Physical Propertie Apparent Dens., g./cc.

Fresh 0. 76 Steamed 0.81 0.90 0. 71 0.77 0.63 0.75 Surface Area, ru /g.-

Fresh 485 486 385 465 342 Steamed 1 205 165 177 155 Analysis:

Na, Percent W 0.03 0.08 0.08 0.06 S04, Percent Wt 0. 09 0. ()9 0.09A1203, Percent Wt.

T a1 10. 5 12.1 12.8 10. 3 Combined 2 0.72 0.32 0.45

EVALUATION OF STEAMED 1 CATALYSTS Conversion, Vol. Percent 51.6 37. 648. 5 47.9 52. 4 48. 9 10 RVP Gasoline, Vol. Percent" 40. 7 32. 2 39.038. 6 40.0 39. 5 05+ Gasoline, Vol. Percent 38.6 30.4 37.3 36.8 38.637.8 Total 04's, Vol. Percent..- 12. 8 8.0 13. 0 12.6 15. 5 12.9 DryGas, Wt. Percent 5.8 3.8 5. 3 5. 3 6.1 5.3 Coke, Wt. Percent 3. 4 2. 32. 4 2. 4 2. 7 2. 5 Delta:

Gasoline, Vol. Percent +3. 2 +2. 4 +3.0 2. 9 2.0 +3. 3 X504, Vol.Percent 3. 9 2. 4 2. 1 -2. 4 -0. 8 -1. 6 Dry Gas, Wt. Percent 0.9 0.4-0.9 0. 8 0.7 1.0 Coke, Wt. Percent +0.1 +0. 5 -0. 6 -0. 6 -0. 7 -0. 6

1 Steamed hours at 1225 F. with 100% steam at atmospheric pressure.

2 Residual A120 after treating catalyst fines with hot 67% H2304 for 24hours.

3 Delta dillerence between experimental catalyst and standardsilica-alumina catalyst at the same conversion.

4 Fines-acid contact. 2 hours at room temperature. *Alg(SO4)3-l8Hz0.

It will be seen from the above data that various sources for the aluminacomponent of the present catalyst may be employed.

Another criterion applied to these preparations showing that thecatalytic alumina should be controlled is summarized in FIGURE 1. Here anumber of catalysts prepared by the method described herein weresubjected to a H 50 extraction test to determine the amount of combinedalumina as silica-alumina. From the data shown graphically in FIGURE 1,it will be seen that the least selective catalyst is one containing themost catalytic non-soluble silica-alumina (2.99 weight percent A1 0 Thiscatalyst was a standard (conventional) silica-alumina made by cogelling6.3 percent A1 0 and adding by base exchange about 3 percent A1 0 duringprocessing. These data shown that the combined alumina content should bekept to less than about 1.5 weight percent and preferably within theapproximate range of 0.5 to 1.5 weight percent to obtain the selectivityadvantage.

We claim:

1. A method for preparing a catalyst consisting of silica and aluminawhich comprises dispersing in a silica sol an amount corresponding tobetween about 5 and about percent by weight of the resulting drycomposite of -a finely divided porous material characterized by asurface area of at least 25 square meters per gram selected from thegroup consisting of (1) alumina and (2) composites diameter of between 1and 5 microns, the concentrations and proportions of reactants beingsuch that the resulting silica sol having said finely divided materialdispersed therein has a pH of between 6 and 11 and an alumina contentcorresponding to cogelled alumina of less than about 1.5 weight percent,permitting the resulting sol to set to a hydrogel, treating theresulting hydrogel at a temperature between about F. and about 220 F.with a dilute aqueous solution of a compound selected from the groupconsisting of acids and acid salts for a period within the approximaterange of /2 to 24 hours when an acid solution is employed, and for aperiod within the approximate range of 8 to 48 hours when an acid saltis employed, washing the hydrogel free of watersoluble matter, dryingand calcining.

2. A method for preparing a catalyst consisting essentially of silicaand alumina which comprises dispersing in a silica sol, prepared byintimately contacting an aqueous acid solution and an aqueous alkalimetal silicate solution, an amount corresponding to between about 5 andabout 40 percent :by weight of the resulting dry composite of a finelydivided porous material selected from the group consisting of (1)alumina and (2) composites of silica and alumina containing at least 40weight percent alumina, which material has a Weight mean particlediameter of between 1 and 5 microns, the concentrations and proportionsof reactants being such that the resulting silica sol having said finelydivided material dispersed therein has a pH of between 7 and 9.5 and analumina content corresponding to cogelled alumina of less than about 1.5weight percent, permitting the resulting sol to set to a hydrogel,treating the resulting hydrogel at a temperature between about 150 F.and about 220 F. with a dilute aqueous solution of a compound selectedfrom the group consisting of acids and acid salts for a period withinthe approximate range of /2 to 24 hours when an acid solution isemployed, and for a period Within the approximate range of 8 to 48 hourswhen an acid salt is employed, washing the hydrogel free ofwater-soluble matter, drying and calcining.

3. A method for preparing a catalyst consisting essentially of silicaand alumina which comprises dispersing in a silica sol, an amountcorresponding to between about 5 and about 40 percent by weight of theresulting dry composite of finely divided porous alumina having asurface area of at least 25 square meters per gram and a weight meanparticle diameter of between 1 and 5 microns, the concentrations andproportions of reactants being such that the resulting silica sol havingsaid finely divided alumina dispersed therein has a pH of between 6 and11 and an alumina content corresponding to cogelled alumina of less thanabout 1.5 weight percent, permitting the resulting sol to set to ahydrogel, treating the resulting hydrogel at a temperature between about150 F. and about 220 F. with a dilute aqueous acid solution for a periodwithin the approximate range of /2 to 24 hours, washing the hydrogelfree of Water-soluble matter, drying and calcining.

4. A method for preparing a catalyst consisting essentially of silicaand alumina which comprises dispersing in a silica sol, an amountcorresponding to between about 5 and about 40 percent by weight of theresulting dry composite of a finely divided clay having a Weight meanparticle diameter of between 1 and 5 microns, characterized by a surfacearea of at least 25 square meters per gram and containing at least 40weight percent alumina, the concentrations and proportions of reactantsbe ing such that the resulting silica sol having said finely dividedclay dispersed therein has a pH of between 6 and 11 and an aluminacontent corresponding to cogelled alumina of less than about 1.5 weightpercent, permitting the resulting sol to set to a hydrogel, treating theresulting hydrogel at a temperature between about 150 F. and about 220F. with a dilute aqueous solution of a compound selected from the groupconsisting of acids and acid salts for a period within the approximaterange of /2 to 24 hours when an acid solution is employed, and for aperiod within the approximate range of 8 to 48 hours when an acid saltis employed, washing the hydrogel free of water-soluble matter, dryingand calcinmg.

5. A method for preparing spheroidal particles of a catalyst consistingessentially of silica and alumina which comprises dispersing in a silicasol an amount corresponding to between about 5 and about 40 percent byweight of the resulting dry composite of a finely divided porousmaterial characterized by a surface area of at least 25 square metersper gram selected from the group consisting of 1) alumina and (2)composites of silica and alumina containing at least 40 weight percentalumina which material has a weight mean particle diameter of between 1and 5 microns, the concentrations and proportions of reactants beingsuch that the resulting silica sol having said finely divided materialdispersed therein has a pH of between 6 and 11 and an alumina content,corresponding to cogelled alumina of less than about 1.5 weight percent,introducing globules of the resulting hydrosol into a column ofWater-immiscible liquid wherein the globules of hydrosol set tospheroidal hydrogel, efl'ecting gelation of said spheroidal hydrosolparticles, treating the resulting hydrogel particles at a temperaturebetween about F. and about 220 F. with a dilute aqueous solution of acompound selected from the group consisting of acids and acid salts fora period Within the approximate range of /z to 24 hours when an acidsolution is employed and for a period within the approximate range of 8to 48 hours when an acid salt is employed, Washing the spheroidalhydrogel particles free of water-soluble matter, drying and calcining.

6. A catalyst composition consisting essentially of silica and aluminawherein the content of alumina attributable to alumina cogelled withsilica is less than about 1.5 weight percent prepared by dispersing in asilica sol an amount corresponding to between about 5 and about 40percent by weight of the resulting dry composite of a finely dividedporous material characterized by a surface area of at least 25 squaremeters per gram selected from the group consisting of (1) alumina and(2) composites of silica and alumina containing at least 40 weightpercent alumina, which material has a weight mean particle diameter ofbetween 1 and 5 microns, the concentrations and proportions of reactantsbeing such that the resulting silica sol having said finely dividedmaterial dispersed therein has a pH of between 6 and 11, permitting theresulting sol to set to a hydrogel, treating the resulting hydrogel at atemperature between about 150 F. and about 220 F. with a dilute aqueoussolution of a compound selected from the group consisting of acids andacid salts for a period within the approximate range of /2 to 24 hourswhen an acid solution is employed and for a period of 8 to 48 hours whenan acid salt is employed, washing the hydrogel free of water-solublematter, drying and calcining.

7. A catalyst composition in the form of spheroids consistingessentially of silica and alumina wherein the alu mina contentattributable to alumina cogelled with silica is less than about 1.5weight percent, prepared by dis persing in a silica sol, an amountcorresponding to between about 5 and about 40 percent by weight of theresulting dry composite of a finely divided porous ma terialcharacterized by a surface area of at least 25 square meters per gramselected from the group consisting of (l) alumina and (2) composites ofsilica and alumina containing at least 40 weight percent alumina, whichmaterial has a weight mean particle diameter of between 1 and 5 microns,the concentrations and proportions of reactants being such that theresulting silica sol having said finely divided material dispersedtherein has a pH of between 6 and 11, introducing globules of theresulting hydrosol in a column of water-immiscible liquid wherein theglobules of hydrosol set to spheroidal hydrogel, eifecting gelation ofsaid spheroidal hydrosol particles, treating the resulting hydrosolparticles at a tern perature between about 150 F. and about 220 F. with.a dilute aqueous solution of a compound selected from the groupconsisting of acids and acid salts for a period in the approximate rangeof /2 to 24 hours when an acid solution is employed, and for a periodwithin the approximate range of 8 to 48 hours when an acid salt isemployed, washing the spheroidal hydrosol particles free ofwater-soluble matter, drying and calcining.

8. A method for preparing a catalyst consisting essentially of silicaand alumina which comprises dispersing in a silica sol an amountcorresponding to between about 5 and about 40 percent by weight of theresulting dry composite of a finely divided porous materialcharacterized by a surface area of at least 25 square meters per gramselected from the group consisting of (l) alumina and (2) composites ofsilica and alumina containing at least 40 weight percent alumina, whichmaterial has a weight mean particle diameter of between 1 and 5 microns,the concentrations and proportions of reactants being such that theresulting silica sol having said finely divided material dispersedtherein has a pH of between 6 and 11 and an alumina content correspond-21 22 ing to cogelled alumina of less than about 1.5 weight ReferencesCited in the file of this patent percent, permitting the resulting s01to set to a hydrogel, treating the resulting hydrogel at a temperaturebe- UNITED STATES PATENTS tween about 150 F. and about 220 F. with adilute 2,437,065 Milliken Nov. 8, 1949 aqueous aluminum acid saltsolution for a period within 5 ,631,983 Milliken Mar. 17, 1953 theapproximate range of 8 to 48 hours, washing the ,669,547 Shabaker Feb.6, 1954 hydrogel tree of water soluble matter, drying and calcin- ,91,95 8 Connor et a1. June 21, 1960 ing the resulting hydrogel. 64,481Cramer et a1 Dec. 13, 1960 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3, 120,496 February 4-, 1964 Charles J. Plank etal,

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 4, line 58 after "aluminafl' first occurrence insert eta alumina,column 11, line 74, for "is" read as column 13, Table V, under theheading "14", line 9 thereof, for "NG CI" read NH CI column l4 line 50,.for "immisible" read immiscible Signed and sealed this 8th day ofDecember 1964,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Aitcsting Officer Commissioner ofPatents

1. A METHOD FOR PREPARING A CATALYST CONSISTING OF SILICA AND ALUMINAWHICH COMPRISES DISPERSING IN A SILICA SOL AN AMOUNT CORRESPONDING TOBETWEEN ABOUT 5 AND ABOUT 40 PERCENT BY WEIGHT OF THE RESULTING DRYCOMPOSITE OF A FINELY DIVIDED POROUS MATERIAL CHARACTERIZED BY A SURFACEAREA OF AT LEAST 25 SQUARE METERS PER GRAM SELECTED FROM THE GROUPCONSISTING OF (1) ALUMINA AND (2) COMPOSITES OF SILICA AND ALUMINACONTAINING AT LEAST 40 WEIGHT PERCENT ALUMINA, WHICH MATERIAL HAS AWEIGHT MEAN PARTICLE DIAMETER OF BETWEEN 1 AND 5 MICRONS, THECONCENTRATIONS AND PROPORTIONS OF REACTANTS BEING SUCH THAT THERESULTING SILICA SOL HAVING SAID FINELY DIVIDED MATERIAL DISPERSEDTHEREIN HAS A PH OF BETWEEN 6 AND 11 AND AN ALUMINA CONTENTCORRESPONDING TO COGELLED ALUMINA OF LESS THAN ABOUT 1.5 WEIGHT PERCENT,PERMITTING THE RESULTING SOL TO SET TO A HYDROGEL, TREATING THERESULTING HYDROGEL AT A TEMPERATURE BETWEEN ABOUT 150*F. AND ABOUT220*F. WITH A DILUTE AQUEOUS SOLUTION OF A COMPOUND SELECTED FROM THEGROUP CONSISTING OF ACIDS AND ACID SALTS FOR A PERIOD WITHIN THEAPPROXIMATE RANGE OF 1/2 TO 24 HOURS WHEN AN ACID SOLUTION IS EMPLOYED,AND FOR A PERIOD WITHIN THE APPROXIMATE RANGE OF 8 TO 48 HOURS WHEN ANACID SALT IS EMPLOYED, WASHING THE HYDROGEL FREE OF WATERSOLUBLE MATTER,DRYING AND CALCINING.